Shrouded valve guide



y 1957 c. cs. GORDON SHROUDED VALVE GUIDE Filed April 30, 1954 CARROLL s; GORDON INVENTOR.

WW (3 Cir/$35 HIS ATTORNEY United States Patent SHROUDED VALVE GUIDE Carroll G. Gordon, Pasadena, Calif.

Application April 30, 1954, Serial No. 426,659

4 Claims. (Cl. 123-188) This invention relates to a shrouded valve guide for the exhaust valves of an internal combustion engine.

It is well known that the exhaust valves become corroded and eventually crack, due to the high temperature and corrosive effect of the exhaust gases. Many efforts have been made to solve this problem, but none has been entirely successful. In even the latest models of some automobiles, the valves sometimes have to be replaced when the car has gone only a few hundred miles.

It is an object of my invention to provide a shrouded valve guide which prevents damage, corrosion and destruction of the valve by acting in two ways. First, it provides a shroud which surrounds the valve stem and prevents as much of the stem as possible from contact with the hot exhaust gases. Second, it provides a guide which contacts the valve stem at a point as near the valve head as possible, in order to conduct heat away from the valve stem. Both of these are necessary in order to provide complete protection for the valve.

It is among the objects of my invention to provide a shrouded valve guide of the type described which may be installed in existing engines or which may be part of the construction of the engine at the time it is made.

My shrouded valve guide may also be used for intake valves as well as exhaust valves, for it prevents excessive cooling of the valve stem and guide by the cold intake mixture, to provide better valve stem lubrication and prevent sticking of the intake valves.

My invention also comprises such other objects, advantages and capabilities as will later more fully appear and which are inherently possessed by my invention.

While I have shown in the accompanying drawings preferred embodiments of my invention, it should be understood that the same are susceptible of modification and change without departing from the spirit of my invention.

Referring to the drawings, Fig. 1 is a longitudinal sectional view of one embodiment of my invention;

Fig. 2 is a longitudinal sectional view of another embodiment of my invention;

Fig. 3 is a longitudinal sectional view of a third embodiment of my invention;

Fig. 4 is a transverse sectional view taken on line 4-4 of Fig. 2.

One embodiment which has been selected to illustrate my invention comprises an exhaust port 10, which is adapted to be opened and closed by the mushroom shaped head 11 of an exhaust valve 12. Valve 12 is provided with a valve stem 13, which is slidably mounted in a valve guide 14, which is attached to the cylinder block 15.

A valve shroud 16 is attached at its lower end to cylinder block 15 and/or valve guide 14 adjacent the bottom of exhaust port by brazing, welding or other suitable attaching means. Shroud 16 extends upwardly adjacent the sides of valve guide 14, but is spaced therefrom. The top of shroud 16 is provided with a cap 17, which extends closely adjacent to valve stem 13, directly beneath head 11.

Cap 17 is spaced at suflicient distance from valve stem r 2,797,677 Patented July 2, 1957 ice 13 to prevent any galling, abrasion or sticking of the valve stem 13 when shroud 16 and cap 17 become expanded due to the heat from the exhaust gases.

The top of valve guide 14 is provided with a square end. The bottom of cap 17 of valve shroud 16 extends in a diagonal line which makes a tangent with the corner of the valve guide 14 to establish a point to point contact between the bottom of cap 17 and the outside top corner of valve guide 14 when the parts are cold. When shroud 16 and cap 17 become heated by the exhaust gases, they expand to pull cap 17 away from contact with guide 14, thus preventing any conduction of heat between shroud 16 and valve guide 14. A dead air space 18 is provided between shroud 16 and valve guide 14. It should be noted that shroud 16 when heated is supported only by its mounting at the bottom of port 10.

A second embodiment of my invention is shown in Fig. 2 of the drawings. In this embodiment, shroud 16 is mounted on a locating ring 19 which is provided at the bottom of port 10 as a part of the cylinder block 15, so that shroud 16 is mounted separately from valve guide 14. The contours of shroud 16 and valve guide 14 are somewhat different from those shown in Fig. 1, but the point to point contact between cap 17 of shroud 16 and the top of valve guide 14 is again used. The type of construction shown in Fig. 2 could be provided by machining an existing cylinder block construction.

A third embodiment of my invention is shown in Fig. 3 of the drawings. In this embodiment, the valve shroud 16 is formed as an integral part of the cylinder block 15, extending upwardly into port 10. This type of construction could only be used by a manufacturer as part of the original construction of the exhaust port of the engine.

In use, the valve shroud 16 acts as a screen to prevent the hot and corrosive exhaust gases from coming into contact with valve stem 13. The top of shroud 16 extends as high as possible, to the point where the mushroom shaped head 11 begins to increase markedly in diameter, so that as much as possible of valve stem 13 is protected from the exhaust gases.

The valve guide 14 also extends as high on valve stem 13 as possible, being positioned closely adjacent to the cap 17 of valve shroud 16. Valve guide 14 extends as high as possible in order to conduct heat away from valve stem 13 at a point as close as possible to the source of heat.

In practice, the positioning of valve shroud 16 and valve guide 14 may best be determined by placing them as high as possible without interfering with the proper operation of the valve. Such interference ordinarily manitests itself in the form of sticking of the valve stem or galling or scouring of the valve stem by cap 17 of shroud 16 or the valve guide 14.

I claim:

1. In combination with an exhaust valve comprising a valve stem having a mushroom shaped head adapted to close an exhaust port, a valve guide extending into said port surrounding said valve stem, said valve guide being in contact with the upper part of said stem adjacent said head and adapted to conduct heat from said stem, a shroud attached at one end adjacent the base of said port, said shroud extending substantially parallel to and spaced from said valve guide, said shroud having an integral cap at the opposite end thereof, said cap having an opening surrounding said valve stem directly beneath said head, said shroud being spaced only far enough from said valve stem to prevent interference with the movement of said valve stem, said cap having a diagonal undersurface, said undersurface extending tangentially to the top of said valve guide to establish line contact therewith when said parts are cold, said shroud and cap adapted to be 3 3 expanded by the hot exhaust gases to break the contact between said shroud and valve guide, said shroud adapted to prevent the exhaust gases from contacting said valve stem or valve guide.

2. In combination with an exhaust valve comprising a valve stem having a mushroom shaped head adapted to close an exhaust port, a valve guide extending into said port surrounding said valve stem, said valve guide being in contact with a substantial portion of said stem and adapted to conduct heat therefrom, a shroud attached at one end adjacent the base of said port, said shroud extending parallel to and spaced from said valve guide, the top of said shroud extending closely adjacent to said valve stem directly beneath said head, the top of said shroud making a slight contact with said valve guide adjacent the top thereof when said parts are cold, said shroud adapted to be expanded by the hot exhaust gases to break said contact, said shroud adapted to prevent the exhaust gases from contacting said valve stem or valve guide.

3. The subject matter of claim 2, the contact between said shroud and valve guide being substantially line contact.

4. The subject matter of claim 2, the top of said shroud being spaced from said valve stem only a sulficient distance to prevent interference with the movement of said valve stem.

References Cited in the file of this patent UNITED STATES PATENTS 2,032,162 Zahodiakin Feb. 25, 1936 2,124,362 Zahodiakin July 19, 1938 2,633,117 Pielstick Mar. 31, 1953 

